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Published on: March 27, 2018
Developmental expression of RFamide-related peptides in the rat central nervous system
Takahiko Yano1, Norio Iijima, Shuji Hinuma
1Pharmacology Research Laboratories I, Pharmaceutical Research Division, Takeda Pharmaceutical Company Ltd., 2-17-85 Juso-Honmachi, Yodogawaku, Osaka 532-8686, Japan.
Abstract:
RFamide-related peptides (RFRP-1 and RFRP-3) have been recently identified in mammals and considered to play significant functional roles in the rat brain. In this study, we report the developmental expression of RFRP mRNA and its immunoreactive neuronal cells and fibers in the rat brain. The RFRP mRNA was expressed in the brain from embryonic day 15 (E15) according to reverse transcription-polymerase chain reaction analysis. We first detected RFRP mRNA expressing neurons in the caudal portion of the hypothalamus at E16 by in situ hybridization analysis. Immunohistochemical analysis showed that RFRP-3 or RFRP-1 immunoreactive neuronal cell bodies were first detected at E16 or E17, respectively. Double-labeling fluorescent immunohistochemical analysis showed that neurons containing both RFRP-1 immunoreactivity (ir) and RFRP-3-ir were detected from E18. We also detected RFRP-1 immunoreactive nerve fiber processes in the forebrain, hypothalamus, thalamus, midbrain, pons and medulla oblongata at prenatal day and the distribution of RFRP-1 immunoreactive nerve fibers in postnatal day 0 (P0) were almost coincident with that in adult. However, localization of RFRP-3 immunoreactive nerve fibers was limited around the RFRP-3 immunoreactive neuronal cell bodies during prenatal days. The distribution of RFRP-3 immunoreactive nerve fibers was first detected in the above areas at P0. The nerve fibers containing only RFRP-3-ir in the thalamus or spinal cord were first appeared at P21 or P28. Our results show that RFRP mRNA was expressed during the neonates and the distribution of RFRP-1 or RFRP-3 immunoreactive nerve fibers would be distinctly regulated in the developing rat brain.
Insights
RFamide-related peptides (RFRP-1 and RFRP-3) mRNA expression begins early in rat brain development. Their neuronal cell bodies and nerve fibers show distinct developmental patterns, with RFRP-1 appearing earlier and more widely than RFRP-3.
Area of Science:
- Neuroscience
- Developmental Biology
- Molecular Biology
Background:
- RFamide-related peptides (RFRP-1 and RFRP-3) are recently identified in mammals.
- These peptides are believed to play significant functional roles in the rat brain.
Purpose of the Study:
- To investigate the developmental expression of RFRP mRNA, immunoreactive neuronal cells, and nerve fibers in the rat brain.
- To understand the distinct developmental regulation of RFRP-1 and RFRP-3 in the central nervous system.
Main Methods:
- Reverse transcription-polymerase chain reaction (RT-PCR) for mRNA detection.
- In situ hybridization for identifying mRNA-expressing neurons.
- Immunohistochemistry to visualize RFRP-1 and RFRP-3 immunoreactive cells and fibers.
- Double-labeling fluorescent immunohistochemistry for co-localization studies.
Main Results:
- RFRP mRNA expression was detected from embryonic day 15 (E15).
- RFRP-3 and RFRP-1 immunoreactive cell bodies were first observed at E16 and E17, respectively.
- Neurons containing both RFRP-1 and RFRP-3 immunoreactivity were detected from E18.
- RFRP-1 nerve fibers were widely distributed prenatally and postnatally, similar to adults.
- RFRP-3 nerve fibers showed limited prenatal distribution, appearing more broadly at postnatal day 0 (P0) and later in specific regions like the thalamus and spinal cord.
Conclusions:
- RFRP mRNA is expressed during neonatal development in the rat brain.
- The distribution patterns of RFRP-1 and RFRP-3 immunoreactive nerve fibers are distinctly regulated during brain development.
- These findings provide insights into the developmental roles of RFRP peptides in the rat nervous system.
